Dynamic noise sampling for unspecified display noise

ABSTRACT

A method includes: displaying, an image on a display by sequentially displaying a plurality of frames of the image, the plurality of frames including a first frame and second frame; performing a first noise sampling scan at a plurality of frequencies at a first time location within a first frame; determining a first frequency from the plurality of frequencies with the lowest noise; performing a first mutual sensing scan at the first frequency; performing, a second noise sampling scan at the plurality of frequencies at a second time location within a second frame of the plurality of frames, the second time location being a different frame location than the first time location; determining a second frequency from the plurality of frequencies with the lowest noise, the second frequency being different from the first frequency; and performing, a second mutual sensing scan at the second frequency.

TECHNICAL FIELD

The present invention relates generally to systems and methods foroperating displays, and in particular embodiments to noise intouchscreen displays.

BACKGROUND

Electronic devices that are designed for user interaction havehistorically utilized external input devices such as keyboards, keypads, and/or mice to capture user input. In recent years, there has beena push from the more traditional methods, as consumers prefer theconvenience of portable devices that can support a more flexiblelifestyle. To this end, there has been a rise in smaller, portable,hand-held electronic devices, such as mobile phones, tablets, gamingsystems, etc. This has given rise to the popularity of touch screens andtouch panel displays as systems for capturing user input. Not only dothey provide the functionality of the traditional electronic devices,but touchscreens provide additional features. For example, given theappropriate software, users are able to utilize touchscreens forsketching, drawing, and various hand writing applications.

Organic light emitting diodes (OLEDs) offer a higher performancedisplay. OLED display provide a high contrast self-illuminating displaywith a low driving voltage and high luminous efficiency. However OLEDdisplays come with their own set of advantages and disadvantages.

A display panel of an OLED based touchscreen may include a plurality ofpixels arranged in rows and columns across a display layer in a matrixlike formation. Each pixel may include an OLED configured to generatelight based on the current driven through it. During operation thetouchscreen may be refreshed (e.g. updated) in each of a plurality ofdisplay frames defined by a vertical synchronization signal (Vsync).During each display frame each row of pixels is updated sequentially andtouch sensing scans (e.g. mutual and self-sensing scans) are performed.

During normal operations, when a color image is being displayed on thetouchscreen, Hsync has a strong effect on the display. The typicalfrequency of noise present on the touchscreen is close to the value ofHsync. If mutual sensing scans used to detect touches made to thetouchscreen are performed at the same frequency as the noise of thetouchscreen, touches that are not actually occurring may be detected.This is known as a ghost touch. Therefore, the frequency of mutualsensing scans can be configured to be a frequency away from Hsync.

However, when a zebra (black and white) image is displayed on atouchscreen, black areas are areas of low voltages on the touchscreenand white areas are areas of high voltages on the touchscreen. The highand low voltages are dense, and have an effect of the capacitance valuessensed by the touchscreen, causing additional noise. Each zebra imagehave a unique noise frequency it generates. Therefore, mutual sensingscans that are performed when a zebra image is displayed may not avoidthe frequency of the zebra image. This may result in a ghost touch.

SUMMARY

In accordance with an embodiment of the present invention, a method foroperating an includes: displaying, on a display of the electronicdevice, an image by sequentially displaying a plurality of frames of theimage, the plurality of frames including a first frame and second frame;performing, on the display, a first noise sampling scan at a first timelocation within a first frame of the plurality of frames, the firstnoise sampling scan being performed at a plurality of frequencies;determining a first frequency from the plurality of frequencies with thelowest noise based on the first noise sampling scan; performing, on atouchscreen of the electronic device, a first mutual sensing scan at thefirst frequency; performing, on the display, a second noise samplingscan at a second time location within a second frame of the plurality offrames, the second noise sampling scan being performed at the pluralityof frequencies, the second time location being a different framelocation than the first time location; determining a second frequencyfrom the plurality of frequencies with the lowest noise based on thesecond noise sampling scan, the second frequency being different fromthe first frequency; and performing, on the touchscreen, a second mutualsensing scan at the second frequency.

In accordance with an embodiment of the present invention, a deviceincludes a plurality of pixels; a touchscreen including a touchscreencontroller; and a non-transitory memory storing instructions to beexecuted in the touchscreen controller to configure the touchscreencontroller to: displaying, on the display, an image by sequentiallydisplaying a plurality of frames of the image, the plurality of framesincluding a first frame and second frame; perform, on the display, afirst noise sampling scan at a first time location within a first frameof the plurality of frames, the first noise sampling scan beingperformed at a plurality of frequencies; determine a first frequencyfrom the plurality of frequencies with the lowest noise based on thefirst noise sampling scan; perform, on the touchscreen, a first mutualsensing scan at the first frequency; perform, on the display, a secondnoise sampling scan at a second time location within a second frame ofthe plurality of frames, the second noise sampling scan being performedat the plurality of frequencies, the second time location being adifferent frame location than the first time location; determine asecond frequency from the plurality of frequencies with the lowest noisebased on the second noise sampling scan, the second frequency beingdifferent from the first frequency; and perform, on the touchscreen, asecond mutual sensing scan at the second frequency.

In accordance with an embodiment of the present application, a methodfor operating an electronic device includes: displaying, on a displaylayer of a touchscreen, an image by sequentially displaying a pluralityof frames of the image; performing, by a touchscreen controller, aplurality of scans on the touchscreen in each of the plurality offrames, each of the plurality of scans including a noise sampling scanperformed on the display layer and a mutual sensing scan performed on atouch sensing layer of the touchscreen; determining, in each of theplurality of frames, a first frequency for a subsequent mutual-sensingscan from a plurality of sampling frequencies based on noise levelsdetermined during a previous noise sampling scan; performing thesubsequent mutual sensing scan at the first frequency; and changing asequence of each of the plurality of scans after each of the pluralityof frames.

In accordance with an embodiment of the present application, a deviceincludes a display including a display layer including a plurality ofpixels; a touchscreen including a touchscreen controller; and anon-transitory memory storing instructions to be executed in thetouchscreen controller to configure the touchscreen controller to:display, on the display layer of the touchscreen, an image bysequentially displaying a plurality of frames of the image; perform aplurality of scans on the touchscreen in each of the plurality offrames, each of the plurality of scans including a noise sampling scanperformed on the display layer and a mutual sensing scan performed on atouch sensing layer of the touchscreen; determine, in each of theplurality of frames, a first frequency for a subsequent mutual-sensingscan from a plurality of sampling frequencies based on noise levelsdetermined during a previous noise sampling scan; perform the subsequentmutual sensing scan at the first frequency; and change a sequence ofeach of the plurality of scans after each of the plurality of frames.

In accordance to an embodiment of the present application, a method foroperating a touchscreen includes: displaying, on a display layer of atouchscreen, an image by sequentially displaying a plurality of framesof the image; performing, by a touchscreen controller, a plurality ofscans on the touchscreen in each of the plurality of frames, each of theplurality of scans including a noise sampling scan performed on thedisplay layer and a mutual sensing scan performed on a touch sensinglayer of the touchscreen, the noise sampling scan being performed at aplurality of different noise sampling frequencies, and a start time ofthe noise sampling scan in each of the plurality of frames beingdetermined based on a frame count of the frame being displayed withinthe plurality of frames; determining, based on the noise sampling scanfor each frame, a noise sampling frequency from amongst the plurality ofdifferent noise sampling frequencies having a lowest noise level forthat frame; and performing, a mutual sensing scan that is performedsubsequent to the noise sampling scan at the noise sampling frequencyhaving the lowest noise level.

In accordance with an embodiment of the present application, a deviceincludes: a display including a display layer including a plurality ofpixels; a touchscreen including a touchscreen controller; and anon-transitory memory storing instructions to be executed in thetouchscreen controller to configure the touchscreen controller to:display, on a display layer of the touchscreen, an image by sequentiallydisplaying a plurality of frames of the image; perform a plurality ofscans on the touchscreen in each of the plurality of frames, each of theplurality of scans including a noise sampling scan performed on thedisplay layer and a mutual sensing scan performed on a touch sensinglayer of the touchscreen, the noise sampling scan being performed at aplurality of different noise sampling frequencies, and a start time ofthe noise sampling scan in each of the plurality of frames beingdetermined based on a frame count of the frame being displayed withinthe plurality of frames; determine, based on the noise sampling scan foreach frame, a noise sampling frequency from amongst the plurality ofdifferent noise sampling frequencies having a lowest noise level forthat frame; and perform, a mutual sensing scan that is performedsubsequent to the noise sampling scan at the noise sampling frequencyhaving the lowest noise level.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1A-1D illustrate an electronic device according to an embodimentof the present application, wherein FIG. 1A illustrates a componentschematic of the electronic device, FIG. 1B illustrates a componentschematic of a display of the electronic device, FIG. 1C illustrates acomponent schematic of a display stack up of the electronic device, andFIG. 1D illustrates a component schematic of a touchscreen of theelectronic device;

FIGS. 2A-2C illustrate schematic views of how a conventional electronicdevice prevents ghost touches using a noise sampling scan, where FIG. 2Aillustrates a schematic view of an conventional electronic devicepreventing ghost touches, FIG. 2B illustrates a graphical representationof a noise sampling scan, and FIG. 2C illustrates a exemplary electronicreadout of mutual sensing values when the electronic device isdisplaying a zebra image and a touch is not occurring on the display;

FIGS. 3A-3B illustrate schematic views of an electronic devicepreventing ghost touches using two different rotating sequences ofsensing scans, wherein FIG. 3A illustrates a schematic view of anelectronic device preventing ghost touches using two different rotatingsequences of sensing scans, and FIG. 3B illustrates an exemplary readoutof mutual sensing values detected by the electronic device when a zebraimage is being displayed and a touch is not occurring on the display ofthe electronic device;

FIG. 4 illustrates schematic views of an electronic device preventingghost touches using four different rotating sequences of sensing scans;and

FIG. 5 illustrates a process flow for preventing ghost touches accordingto an embodiment of the present application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Conventional organic light emitting diode (OLED) devices may include adisplay panel that may include a plurality of pixels arranged in rowsand columns across a display layer in a matrix like formation. Duringoperation, the OLED display may be refreshed in each of a plurality offrames distinguished by a frequency of a vertical synchronization signal(Vsync). The OLED display may be updated by refreshing each row ofpixels sequentially from top to bottom of the display in each frame inaccordance with a horizontal synchronization signal (Hsync).

A mutual sensing scan is performed on a touchscreen of an OLED displayto determine user touch. The sensitivity of the mutual sensing scandepends on various noise sources. If the background noise is high, thesensitivity of mutual sensing will be lower because the touch has tointroduce a significant change in mutual capacitance that is above thedetection limit. Typically, mutual sensing can be performed over a rangeof frequencies. However, in practice, the noise levels can be differentat different scan frequencies used for mutual sensing. The exactfrequency with the lowest noise level can not be determined apriori.

If significant noise is present when the mutual sensing scan isperformed, the results of the mutual sensing may detect erroneous touchunless the sensitivity of the mutual sensing is reduced significantly byincreasing the detection limit. In other words, a touch on thetouchscreen may be detected when nothing is touching the touchscreen.This is known as a ghost touch. During normal operations, when a colorimage is being displayed on the touchscreen, the horizontalsynchronization signal (Hsync) has a strong effect on the display. Thetypical frequency of noise present on the touchscreen is close to thevalue of Hsync. If mutual sensing scans used to detect touches made tothe touchscreen are performed at the same frequency as the noise of thetouchscreen, ghost touches may occur.

Conventionally, to prevent ghost touches when displaying a zebra image(any pattern of black and white), a noise sampling scan may be performedin each of the plurality of frames. Noise sensing scans are usuallyperformed between a self-sensing scan and a mutual sensing scan in eachframe. During the noise sampling scan, noise levels on the displaycorresponding to each frequency from a plurality of frequencies isdetected. Due to the duration of the frame, the duration of aself-sensing scan, and a duration of the mutual sensing scan, the noisesampling scan is performed for a limited amount of time of the display.Also because the display is being updated row-by-row, the noise samplingscan is performed on only the portion of the touchscreen that is beingupdated during the noise sampling scan.

However, zebra (black and white) images on the touchscreen include highvoltage areas on the display where white is displayed and low voltageareas on the display where black is being displayed. This contrastingarray of voltages is packed within a small area and can cause changes tothe capacitances sensed on the touchscreen. In addition, the noise fromsuch zebra images varies with frequency. Therefore, to minimize thenoise generated from the zebra image, the frequency with the lowestnoise value in the noise sampling scan is selected and the subsequentmutual sensing scan is performed at the selected frequency. This isknown as frequency hopping.

However, in some cases, only a portion of the image being displayedcontains a zebra pattern. For example, the portion of the display orframe in which the noise sampling scan is being performed may not have azebra pattern while the rest of the portion being displayed may containa zebra pattern. In such cases, the noise sampling scan does not detectthe zebra pattern and therefore the system is unaware of the associatedhigher noise. The display may thus select a frequency that isinappropriate for the zebra pattern. Consequently, the noise associatedwith the zebra pattern, i.e., the zebra pattern noise may cause a falsedetection and result in ghost touch.

Embodiments relate to dynamic noise sampling for unspecified displaynoise. Embodiments of the present application disclose a method forrotating the start time of noise sampling scans frames to prevent aghost touch. In other words, the portion of the display that is scannedduring a noise sampling scan changes between frames, increasing coverageof noise sampling scans across the display.

FIGS. 1A-1D illustrate an electronic device according to an embodimentof the present application, wherein FIG. 1A illustrates a componentschematic of the electronic device, FIG. 1B illustrates a componentschematic of a display of the electronic device, FIG. 1C illustrates acomponent schematic of a display stack up of the electronic device, andFIG. 1D illustrates a component schematic of a touchscreen of theelectronic device.

Referring to FIG. 1A, an electronic device wo may include a display 102,a touchscreen controller 104, and a system on a chip 106. The electronicdevice wo may be a smart phone, a GPS device, a tablet computer, amobile media player, a laptop, a gaming system, a personal computer, orany other electronic device that may utilize touch sensitive display.

The display 102 may be an organic light emitting diode (OLED) display,an LED display, or any other type of display. The display 102 mayinclude a plurality of pixels in a display layer configured to displayan image. As understood by those with ordinary skill in the art, thedisplay layer of the display 102 may include of the plurality of pixelspositioned at each of the intersections between the data lines and scanlines. The plurality of scan lines may extend across the rows of thedisplay 102, and data lines that extend across the columns of thedisplay 102 in a matrix like formation.

The display may also include a touchscreen (e.g. a touch sensing layer)configured to detect touches made on the display 102. This will be shownin more detail below.

The touchscreen controller 104 may perform various methods with respectto the display. In various embodiments, the touchscreen controller 104may be a processor that analyzes information and carries out a series ofexecutable scripts, e.g., stored in a memory no. In one or moreembodiments, the processor may comprise an application-specificintegrated circuit (ASIC) device, a central processing unit (CPU), orany other processing unit known in the art. In various embodiments, thetouchscreen controller 104 may comprise a number of separate computingunits such as cores integrated within one processor, or distinctseparate processing chips.

In various embodiments, the touchscreen controller 104 may include, ananalog block 108, a digital block 112. The analog block 108 may includea plurality of analog circuits configured to measure capacitances acrossdisplay 102 and convert them into digital values. The digital block 112may comprise a variety of digital logic circuits such as DACs or digitalcontrol systems configured to obtain digital touch data from the analogblock 108, process the digital touch data and store them into memory no.

The memory 110 may be programmed for short term and/or long term memorystorage. The memory 110 may comprise various programs to be executed inthe touchscreen controller 104. The memory 110 may include both volatileand non-volatile memories. The memory 110 is designed to retaininformation generated by the touchscreen controller 104 so it can berecalled at a later time.

In various embodiments, the system on a chip 106, may also be known asan application processor, and may comprise a processor, interface,circuitry, and/or the like configured to direct the flow of input andoutput data to the display 102 and the associated touchscreencontroller. The system on a chip 106 may be configured to transmit imagedata and synchronization signals to the touchscreen controller 104. Inother words, the system on a chip 106 may be configured to transmitimage data corresponding to a plurality of frames on an image.

In various embodiments, the synchronization signals transmitted by thesystem on a chip 106 may include a horizontal synchronization signal(Hsync) and a vertical synchronization signal (Vsync). The touchscreencontroller 104 may receive the image data and transmit processed imagedata to the pixels on the display 102 based on Hsync and update theimage displayed based on Vsync. In other words, each time Vsync istransmitted, the frame of an image currently being displayed may berefreshed to the next frame of the image.

As understood by those with ordinary skill in the art, the frame of theimage being displayed may be refreshed (e.g. updated) in each of aplurality of display frames defined by Vsync. When Vsync is transmitted(i.e. logic high), the frame of the image being displayed may berefreshed. Therefore, the frequency of Vsync distinguishes each of theframes.

During each of the frames, the touchscreen controller 104 may updateeach row of pixel circuits sequentially in accordance with Hsync. Thetouchscreen controller 104 may update each row of pixels of the displaytop-to-bottom in accordance with Hsync is each frame. In other words adifferent row of pixels may be updated each time Hsync is transmitted(i.e. is logic high). Therefore, Hsync has a higher frequency thanVsync.

Additionally, the touchscreen controller 104 may be configured to detecttouches on the display 102 via a touchscreen. In other words, thetouchscreen controller 104 may be configured to send touch drivingsignals (TDS) to the touchscreen, receive touch sensing signals (TSS) inreturn from the touchscreen, process the TSS to determine coordinates oftouch, and report them to the system on a chip 106. Then based on thetouch data collected from scanning, the touchscreen may be used by thetouchscreen controller 104 to determine the coordinates of touch, andreport them to the system on a chip 106. Then, the system on a chip 106may provide an output to the display 102 based on the reportedcoordinates of touch.

As understood by those with ordinary skill in the art, when noise ispresent on the display 102, if a mutual sensing scan is performed at thesame frequency as the noise, the mutual sensing scan may detect a ghosttouch on the display 102.

Typically noise may be generated on the display 102 based on thebrightness of the colors being generated by each pixel. The brighter thecolor of a pixel the higher the voltage. In normal operation, when colorimages are being displayed on the touchscreen, the high frequency ofHsync has a strong effect on the noise on the display. In other words,the frequency of the noise on the touchscreen typically follows Hsync.Therefore, the frequency of the mutual sensing scans can be configuredto avoid Hsync.

However, when zebra (black and white) patterns are displayed, anincrease in the variation between high voltages in white areas and thelow voltages in the black areas generate additional noise. Each zebraimage may generate noise on the display 102 that peaks at a frequencydifferent than the frequency of Hsync and may not be easily avoided bythe frequency used in mutual sensing scans.

Conventionally, to avoid performing mutual sensing scans at thefrequency at which the noise has a maxima (or generally high), noisesampling scans are performed in each frame. Noise sampling scans areconventionally performed once in each frame along with a self-sensingscan and a mutual sensing scan. In order to have enough time to performeach of the scans, the noise sampling scan is performed during a portionof each frame.

Noise sampling scans are conventionally performed over a plurality ofdifferent frequencies. This allows a noise level to be determined foreach different frequency. Then the frequency having the lowest noisevalue may be used as the frequency for performing a mutual sensing scan.This allows the mutual sensing scan to be changed so as to be performedat a different frequency than the frequency of the peak noise caused bythe zebra pattern.

Because the display 102 is being updated row by row, and due to timeconstraints, a noise sampling scan can only be performed over a portionof the display 102. Conventionally noise sampling scans are performed ata same start time in each frame and over a same portion of the display102.

The inventors of this application have identified that in instanceswhere the portion of the display 102 being scanned does not indicate azebra pattern is being displayed, frequency hopping will not occur. Forexample, if an image with zebra pattern is being displayed but theportion of the display that is scanned is only a white (or black)portion of the display, the noise levels of the image may bemiscalculated. In other words, in each noise sampling scan, due to thesmall noise values generated by the all white (or all black) portion ofthe image, the touchscreen controller would be misguided to perform themutual sensing scan at a frequency with a higher noise. This may resultin ghost touch.

Advantageously embodiments of the present application disclose a methodfor rotating the start time of noise sampling scans between each frameto prevent a ghost touch. In other words, the portion of the displaythat is scanned during a noise sampling scan changes between frames,increasing the coverage of noise sampling scans.

FIG. 1B illustrates a schematic of the display. In various embodiments,the display 102 may include a touchscreen 118 (e.g. a touch sensinglayer) and a display layer 116. The touchscreen 118 and the displaylayer 116 may be situated on the front facing side of the electronicdevice 100.

FIG. 1C illustrates a display stack-up of the display 102. The displaystack-up of the display 102 may include a plurality of layers. Invarious embodiments, the display 102 may comprise a cover film 120, thetouchscreen 118, a core 122, an encapsulation film 124, and an OLEDlayer 126.

The OLED layer 126 may comprise a plurality of OLED elements (e.g.,pixels) formed across rows and columns of the touchscreen in a matrixlike formation. The OLED elements may be configured to transmit lighthaving a color (such as red, green, or blue) with a brightness based onthe current they are driven with to display each of the frames of theimage. As described above, the color and brightness displays by OLEDelements are refreshed in display frames according to a verticalsynchronization signal (Vsync) and a horizontal synchronization signal(Vsync).

The encapsulation film 124 may be formed and in direct contact with theOLED layer 126. The encapsulation film 124 may function to preventoxygen, water, or moisture from external sources reaching into anddamaging the OLED layer 126. The encapsulation film 124 may comprise oneor more layers of material. For example, the encapsulation film 124 maycomprise silicon dioxide, silicon nitride, or any other encapsulationfilms known in the art.

A core 122 may be formed over the encapsulation film 124. The core 122may be used for controlling the characteristics of the display 102 suchas external light reflection, color accuracy, luminance, and so on. Forexample, the core 122 may include multiple layers such as a reflectioncontrol layer that includes color filters, a lens layer corresponding toeach OLED element of the OLED layer, and the like.

The touchscreen 118 may be formed over the core 122. The touchscreen 118may be a capacitive touch panel configured to detect touches made to thedisplay 102. This will be explained in more detail below. Nevertheless,it should be clear that noise generated at the OLED layer 126 can bepicked up at the touchscreen 118.

The cover film 114 may be a protective layer to protect the touchscreen118. The cover film 114 may comprise a transparent material such as athin layer of glass including silicon dioxide.

The display stack-up described in FIG. 1C is for example purposes onlyand is not limited by this application. Additional layers known in theart may also be included in the display stack up of the display 102.

FIG. 1D illustrates a schematic of the touchscreen 118. In variousembodiments, the touchscreen 118 may comprise drive lines Dr1-Dr4 andsense lines SS1-SS4 that span the entirety of the touchscreen 118 in agrid-like fashion that are operable by the touchscreen controller 104.In various embodiments, the drive lines Dr1-Dr4 may be formed in rowsacross the touchscreen 118 and the sense lines SS1-SS4 may be formed incolumns across the touchscreen 118. In other embodiments, the drivelines Dr1-Dr4 may be formed in columns across the touchscreen 118 andsense lines SS1-SS4 may be formed in columns across the touchscreen 118.In various embodiments, the number of drive lines may be equal to thenumber of sense lines. Although four drive lines and four sense linesare illustrated in FIG. 1D, this is not indicative of the number ofdrive and sense lines that may be present on the touch sensing layer.The number of drive and sense lines used are not limited by thisapplication.

The drive lines Dr1-Dr4 and the sense lines SS1-SS4 may overlap incertain embodiments. While FIG. 1F depicts the drive lines Dr1-Dr4 andthe sense lines SS1-SS4 overlapping in an orthogonal manner, they mayoverlap other than orthogonally such as being interleaved or at variousangles.

The drive lines Dr1-Dr4 and the sense lines SS1-SS4 may have ameasurable mutual capacitance at their intersections as to form a matrixof mutual capacitors with mutual capacitances 134.

In various embodiments, the drive lines Dr1-Dr4 may be coupled to drivecircuitry 130 and the sense lines SS1-SS4 may be coupled to sensecircuitry 128 of the touchscreen controller 104. As appreciated by thosewith ordinary skill in the art, each of the drive lines and the senselines may also have a self-capacitance 136 that is measurable. In otherwords, the drive lines Dr1-Dr4 and the sense lines SS1-SS4 are operablein mutual sensing mode and a self-sensing mode.

FIGS. 2A-2C illustrate schematic views of a conventional electronicdevice to prevent ghost touches using a noise sampling scan, where FIG.2A illustrates a schematic view of an conventional electronic devicepreventing ghost touches, FIG. 2B illustrates a graphical representationof a noise sampling scan, and FIG. 2C illustrates a exemplary electronicreadout of mutual sensing values when the electronic device isdisplaying a zebra image and a touch is not occurring on the display.

Referring to FIG. 2A, conventionally, an electronic device 100 performsa self-sensing scan 202, a noise sampling scan 204, and a mutual sensingscan 206 within a duration of a frame 201.

Each of the scans is performed in the following order in each of thedisplays frames: the self-sensing scan 202, the noise sampling scan 204,and then the mutual sensing scan 206. Each of the scans is alwaysperformed at the same position in each of the frames.

As described above, because the noise sampling scan 204 is performed atthe same position in each frame, a same portion 210 of the display 102may be scanned in each frame. In other words, in FIG. 2A even though azebra image is being displayed, the portion 210 of the display 102 beingscanned in each frame is only displaying white.

Referring to FIG. 2B, the noise sampling scan 204 may be performed at aplurality of frequencies. For example, the noise sampling scan 204 maybe performed at a first frequency during a first duration 214, a secondfrequency during a second duration 216, and a third frequency during athird duration 218. The first duration 214, the second duration 216, andthe third duration are each shorter than a duration of the noisesampling scan 212.

The noise level between pixels of the display 102 within the portion 210of the display 102 may be sampled at each frequency. Then the frequencyhaving the lowest noise level may be selected, and the mutual sensingscan 206 in the frame 201 may be performed at that frequency.

As understood by those with ordinary skill in the art, when noise ispresent on the display 102, if a mutual sensing scan is performed at thesame frequency as the noise, the mutual sensing scan may detect a ghosttouch on the display 102. The inventors of this application haveidentified that if a zebra pattern is being displayed, but the portion210 of the display 102 being sampled is only showing white (or black)(i.e., does not include the zebra pattern), the frequency selected bythe noise sampling scan 204 may not avoid the frequency of the noisecaused by a zebra pattern. Because the same portion 210 of the display102 is being scanned during the noise sampling scan that is onlydisplaying white, the zebra pattern in the image will never be detectedand the mutual sensing scan will sense ghost touches.

Referring to FIG. 2C, readout 222 may be generated by the touchscreencontroller 104 when such a zebra pattern image is being displayed and atouch is not occurring on the display 102. When a touch is not beingmade on the display 102, the mutual sensing values should be close tozero. However, due to the noise of the zebra pattern image and becausethe same portion 210 (all white portion) of the display 102 was scannedin each noise sampling scan, the mutual sensing values may be indicativeof the additional capacitances (noise) sensed from the zebra patternimage. In other words, the magnitudes of the mutual sensing valuesindicate changes in capacitances that are not due to a touch, butbecause the touchscreen is unaware of this noise, a touch is reported tothe system on a chip 106.

Advantageously, to prevent the occurrence of ghost touches, embodimentsof the present application rotate the time location of the noisesampling scan between frames. One advantage of this is that noisesampling scans will be performed on different portions of the display,allowing for a zebra image to be detected and frequency hopping to takeplace preventing ghost touches.

FIGS. 3A-3B illustrate schematic views of an electronic devicepreventing ghost touches using two different rotating sequences ofsensing scans, wherein FIG. 3A illustrates a schematic view of anelectronic device preventing ghost touches using two different rotatingsequences of sensing scans, and FIG. 3B illustrates an exemplary readoutof mutual sensing values detected by the electronic device when a zebraimage is being displayed and a touch is not occurring on the display ofthe electronic device.

Referring to FIG. 3A, in each of a plurality of frames, a noise samplingscan, a self-sensing scan, and two mutual sensing scans may each beperformed during a duration of a frame 201. In other words, each mutualsensing scan may be divided into two mutual sensing scans.

In each frame, the scans may be performed in rotating sequences. Inother words, noise sampling scans may be performed at rotating timelocations within the duration 201 of a frame. Advantageously, becauseeach mutual sensing scan may be divided into two mutual sensing scans,each of the scans may be performed in multiple rotating sequences. Alsodividing mutual sensing scans allows for fast frequency hopping becausetwo different mutual sensing scans in a same frame may be performed atdifferent frequencies.

FIG. 3A illustrates an embodiment in which the scans are performed in atwo frame rotation.

A first sequence, defined as order number zero may be as follows: aself-sensing scan 306, a first noise sampling scan 304, and a firstmutual sensing scan 307, and a second mutual sensing scan 308. A secondsequence defined as order number one may be as follows: a self-sensingscan, a first mutual sensing scan 307, a second noise sampling scan 320,and then a second mutual sensing scan 308. These two sequences are usedfor example purposes only. Any two sequences of the scans may be used.

In this illustrative embodiment, for each frame, a specific sequence isselected between the first sequence and the second sequence. Thesequence of the scans used in each frame may be determined based on acurrent frame count, the order numbers of the sequences, and the numberof sequences to be used, which is two in this example embodiment. Thespecific sequence to be used in a frame may be determined by determiningthe modulus of the current frame count with the number of sequences tobe used, i.e., current frame count mod number of sequences. The sequencecorresponding to the order number that is equal to the current framecount mod number of sequences is selected to be the sequence for thatframe.

Referring back to FIG. 3A, at a first frame 302, the current frame countis zero. The modulus between zero and two is equal to zero. Thereforethe first sequence (order number zero) is used in the first frame 302.

Each of the scans may be performed according to the first sequence inthe first frame 302. In other words, the sequence of the scans in thefirst frame 302 may be as follows: a self-sensing scan 306, a firstnoise sampling scan 304, a first mutual sensing scan 307, and then asecond mutual sensing scan 308. The first noise sampling scan 304 may beperformed at a first time location 312 of the first frame 302.

The first noise sampling scan 304 may be performed in the same mannerdescribed above. Because the display 102 is being updated row by rowstarting at the beginning of each frame, and because the time of thenoise sampling scans are time-constrained so that each scan can beperformed in a single frame, noise sampling scans can only be performedover a portion of the display 102. In other words, the noise samplingscans may be performed while the display 102 is being refreshed.Therefore, the first noise sampling scan 304 may be performed over afirst portion 305 of the display 102 at a plurality of frequencies. Thefirst portion 305 is the portion of the display being updated during thefirst time location 312.

As explained above, during each noise sampling scan, a noise levelacross a portion of the display 102 is determined at differentfrequencies. The frequency with the lowest noise level is selected and asubsequent mutual sensing scan is performed at (e.g. after frequencyhopping) to the selected frequency. In various embodiments, becausenoise sampling scans are not necessarily performed before each mutualsensing scan in each frame, the frequency determined from a prior noisesampling scan may be used in each subsequent mutual sensing scan until anext noise sampling scan is performed.

During the first noise sampling scan 304, a noise level of the firstportion 305 may be determined for each of the plurality of frequencies.The frequency having the lowest noise level may be selected as a firstfrequency. Then the first mutual sensing scan 307, and the second mutualsensing scan 308 of the first frame 302 may be performed at the firstfrequency.

In various embodiments, during the mutual sensing scans, the touchscreencontroller 104 may determine each of the mutual capacitances 134 at eachintersection of a sense line and a drive line and convert mutualcapacitances 134 to digital values. The digital values are known asmutual sensing values. Then based on the mutual sensing values, thetouchscreen controller 104 may determine coordinates of a touch on thetouchscreen 118 (if any) for the first frame 302. Because two mutualsensing scans are performed in the first frame 302, the mutual sensingvalues of the first mutual sensing scan 307 and the second mutualsensing scan 308 of the first frame 302 may be averaged to determine themutual sensing values determined in the first frame 302.

However, as described above, if an image with zebra pattern (simply azebra image) is being displayed, there is a possibility that the firstportion 305 may only be displaying all white (or all black). In thiscase, the frequency of the noise is indicative of an all-white imagewith little noise and not a zebra image. Therefore, if the first portion305 of the display is scanned in the noise sampling scan in each frame,the frequencies selected in each frame may be not be able to hop toavoid performing a mutual sensing scan at the frequency of the zebraimage.

Advantageously, as described above, the time location of the noisesampling scan may be rotated between frames so that a different portionof the display 102 is scanned in a subsequent noise sampling scan.

After the first frame 302, the current frame count is one. The modulusbetween one and two is one. Therefore, the second sequence (order one)is used in a second frame 316.

The order of scans in the second frame 316 may be as follows: aself-sensing scan 306, a first mutual sensing scan 307, a second noisesampling scan 320, and then a second mutual sensing scan 308.

Due to the change in order of the scans, the second noise sampling scan320 may be performed at a second time location 324. Because the secondnoise sampling scan 320 is performed after the first mutual sensing scan307 in the second frame 316, the second time location 324 may occurafter the first time location 312.

Therefore, the second noise sampling scan 320 may scan a second portion325 of the display 102 to determine a second frequency.

As described above, because the first mutual sensing scan 307 in thesecond frame 316 is performed prior to the second noise sampling scan320, it may be performed at the first frequency. On the other hand,because the second mutual sensing scan 308 of the second frame 316occurs after the second noise sampling scan 320, it may be performed atthe second frequency.

In various embodiments, a rolling average of each of the mutual sensingvalues determined from each mutual sensing scan may be kept. In otherwords, coordinates of a touch (if any) in the second frame 316 may bedetermined by taking the average of the mutual sensing values determinedfrom the first mutual sensing scan 307 in the first frame 302, thesecond mutual sensing scan 308 in the first frame 302, the first mutualsensing scan 307 in the second frame 316, and the second mutual sensingscan 308 in the second frame 316.

On the other hand, in certain embodiments, the coordinates of a usertouch in each frame may be determined by taking the average of both themutual sensing scans in a single frame. For example, the coordinates ofa user touch the second frame 316 may be determined by taking theaverage of the mutual sensing values detected by the first mutualsensing scan 307 in the second frame 316, and the second mutual sensingscan 308 in the second frame 316.

Next, at a third frame 326, the current frame count is now two. Themodulus between two and two is equal to zero. Therefore, the firstsequence of scans may be reused.

Therefore, the sequence of the scans in the third frame 326 may be asfollows: a self-sensing scan 306, a third noise sampling scan 328, afirst mutual sensing scan 307, and then a second mutual sensing scan308.

Because FIG. 3A illustrates a two frame rotation, in the third frame326, the third noise sampling scan 328 may be performed at the firsttime location 312 to determine a third frequency. The third frequencymay be the same or different than the first frequency depending on theframe of the image displayed in the third frame. Then in the same mannerdescribed above, a first mutual sensing scan 307 and a second mutualsensing scan 308 may be performed in the third frame 326 at the thirdfrequency. In embodiments where more than two frames (scan sequences)are used, the third noise sampling scan 328 may be performed at alocation different than the first time location 312 and the second timelocation 324. This will be shown in detail below.

Then, based on the mutual sensing values collected, coordinates of atouch by a user in the third frame 326 may be determined based on arolling average of all the mutual sensing values collected in eachprevious frame, or an average of the mutual sensing data collected bymutual sensing scans in the third frame.

Alternatively, the frequency determined by a noise sampling scan in aprevious frame may be used as the frequency of a mutual sensing scan inthe subsequent frame. For example, the first mutual sensing scan 307 andthe second mutual sensing scan 308 in the second frame 316 may beperformed at the first frequency. The first mutual sensing scan 307 andthe second mutual sensing scan 308 in the third frame 326 may beperformed at the second frequency and so on.

In some embodiments, the frequencies used for mutual sensing scans maybe determined based on rolling average of the noise values determinedfor each of the plurality of frequencies in each frame. For example, thenoise values determined for the different frequencies determined duringthe second noise sampling scan 320 may be averaged with the noise valuesdetermined for the different frequencies determined during the firstnoise sampling scan 304. The frequency having the lowest average noisevalue may be used as the second frequency. This may be repeated for eachof the frames. For example, the third frequency may be determined basedon the average noise levels for each frequency determined in the firstnoise sampling scan 304, the second noise sampling scan 320, and thethird noise sampling scan 328.

Referring to FIG. 3B, readout 334 may be generated by the touchscreencontroller 104 when a zebra image is being displayed and a touch is notoccurring on the display 102. Advantageously, as shown in readout 334,the mutual sensing values are close to zero and a ghost touch will notbe reported to the system on a chip 106.

FIG. 4 illustrates schematic views of an electronic device preventingghost touches using four different rotating sequences of sensing scans.

Referring to FIG. 4 , four sequences of scans may be rotated betweenfour different frames. In other words, a fourth frame 410 may occurbefore the first frame 302.

In a first sequence, defined as order zero, the sequence of scans may beas follows: a noise sampling scan, a self-sensing scan, a first mutualsensing scan, and then a second mutual sensing scan. In a secondsequence, defined as order one, the sequence of scans may be as follows:a self-sensing scan, a noise sampling scan, a first mutual sensing scan,and then a second mutual sensing scan. In a third sequence, defined asorder two, the sequence of scans may be as follows: a self-sensing scan,a first mutual sensing scan, a noise sampling scan and then a secondmutual sensing scan. In a fourth sequence, defined as order three, thesequence of scans may be as follows: a self-sensing scan, a first mutualsensing scan, a second mutual sensing scan, and then a noise samplingscan.

Referring back to FIG. 4 , at the fourth frame 410, the current framecount is equal to zero. Therefore, the first sequence of scans is used.Therefore, the order of scans in the fourth frame 410 is as follows: afourth noise sampling scan 402, a self-sensing scan 306, a first mutualsensing scan 307, and a second mutual sensing scan 308.

The fourth noise sampling scan 402 may be performed over a fourth timelocation 404 and cover a fourth portion 406 of the display 102 todetermine a fourth frequency in the same manner described above. Invarious embodiments, each mutual sensing scan that is performed betweennoise sampling scans may be performed at the previous determinedfrequency. Therefore, the first mutual sensing scan 307 and the secondmutual sensing scan 308 in the fourth frame 410 may be performed at thefourth frequency.

At the first frame 302, the current frame count is one, therefore theorder number used is one. Therefore, the second sequence of scans isused. Therefore, the order of scans in the first frame 302 is asfollows: a self-sensing scan 306, the first noise sampling scan 304, afirst mutual sensing scan 307, and then a second mutual sensing scan308.

The first noise sampling scan 304 may be performed over the first timelocation 312 and cover the first portion 305 of the display 102 todetermine a first frequency in the same manner described above. Becausethe first noise sampling scan is performed prior to the mutual sensingscans in the first frame 302, the first mutual sensing scan 307 and thesecond mutual sensing scan 308 in the first frame 302 may be performedat the first frequency.

On the other hand, as described above, the noise levels determinedduring the fourth noise sampling scan 402, and the first noise samplingscan 304 may be averaged. Then the first frequency may be determinedbased on the frequency having the lowest average noise levels.

Alternatively, as described above, the first mutual sensing scan 307 andthe second mutual sensing scan 308 in the first frame 302 may beperformed at the fourth frequency.

At the second frame 316, the current frame count is two, therefore, thecurrent order number used is two. Therefore, the third sequence of scansis used. Therefore, the order of the scans in the second frame 316 is asfollows: a self-sensing scan 306, a first mutual sensing scan 307, thesecond noise sampling scan 32 o, and then a second mutual sensing scan308.

The second noise sampling scan 320 may be performed over the second timelocation 324 to determine a second frequency in the same mannerdiscussed above. Alternatively, the second frequency may be determinedbased on the average noise levels for the different frequenciesdetermined from the fourth noise sampling scan 402, the first noisesampling scan 304, and the second noise sampling scan 320.

As described above, because the first mutual sensing scan 307 in thesecond frame occurs prior to the second noise sampling scan, the firstmutual sensing scan 307 may be performed at the first frequency and thesecond mutual sensing scan 308 may be performed at the second frequency.Alternatively, both mutual sensing scans in the second frame 316 may beperformed at the first frequency.

At the third frame 322, the current frame count is three, therefore, thecurrent order number used is three. Therefore, the fourth sequence ofscans is used. Therefore, the order of the scans in the third frame 322is as follows: a self-sensing scan 306, a first mutual sensing scan 307,a second mutual sensing scan 308, and then a third noise sampling scan328.

The third noise sampling scan 328 may be performed over a third timelocation 412 to determine a third frequency in the same manner discussedabove. Here, because the third noise sampling scan 328 is performed at athird time location 412 instead of the first time location 312, like inFIG. 3A, the third noise sampling scan may cover a third portion 408 ofthe display instead of the first portion 305. This advantageously allowsfor even better coverage of noise sampling scans across the display 102.

Alternatively, the third frequency may be determined based on theaverage noise levels for the different frequencies determined from thefourth noise sampling scan 402, the first noise sampling scan 304, thesecond noise sampling scan 320, and the third noise sampling scan 328.

Because the first mutual sensing scan 307 and the second mutual sensingscan 308 in the third frame 322 are performed prior to the third noisesampling scan 328, they may both be performed at the second frequency.

However, in embodiments, in which the frequency used from the previousframe is used in the next frame, a fifth frame occurring after the thirdframe 322 would follow the first scan sequence and use the thirdfrequency for both mutual sensing scans.

Although FIG. 3A illustrates a two sequence rotation and FIG. 4illustrates a four frame rotation, this is for example purposes only.Any suitable number of sequences may be used, for example, a threesequence rotation or a five sequence rotation.

FIG. 5 illustrates a process flow for preventing ghost touches accordingto an embodiment of the present application.

Referring to block 502, and described with reference to FIG. 1A, animage may be displayed on a display 102 of an electronic device 100. Invarious embodiments, the image may be a media such as a video displayedover a plurality of frames or simply a single image which iscontinuously refreshed over a plurality of frames. The frame of theimage displayed in each of the plurality of frames may be updated(refreshed) according to a vertical synchronization signal (Hsync) and avertical synchronization signal (Vsync) in the same manner describedabove.

As next illustrated in block 504, and described with reference to FIGS.3A and 4 , a first noise sampling scan 304 is performed at a first timelocation 312 within a first frame 302. The first noise sampling scan 304may be performed at a plurality of frequencies in the same mannerdescribed above.

As next illustrated in block 506, and described with reference to FIGS.3A and 4 , a first frequency is determined as the frequency from theplurality of frequencies with the lowest noise based on the first noisesampling scan 304.

As next illustrated in block 5 o 8, and described with reference toFIGS. 3A and 4 , a first mutual sensing scan may be performed, on thetouchscreen 118 of the electronic device 100, at the first frequency.For example, referring to both FIGS. 3A and 4 , in the first frame 302,a first mutual sensing scan 307 in the first frame 302 may be performedat the first frequency.

Also, as described above, because a first mutual sensing scan 307 in thesecond frame 316 is performed prior to a second noise sampling scan 320,a first mutual sensing scan 307 may be performed in the second frame 316at the first frequency.

In various embodiments, after performing both mutual sensing scans inthe first frame 302, coordinates of a touch on the touchscreen 118 maybe determined based on an average of the mutual sensing valuesdetermined in the first mutual sensing scan 307 and the second mutualsensing scan 308 performed in the first frame 302.

As next illustrated in block 510, and described with reference to FIGS.3A and 4 , a second noise sampling scan 320 may be performed at a secondtime location 324 within a second frame 316 to determine a secondfrequency. As described above the second noise sampling scan 320 may beperformed at the same plurality of frequencies used in the first noisesampling scan 304. Advantageously, the scans performed in the secondframe 316 may be performed in a different sequence than the scansperformed in the first frame 302. Therefore, the second time location324 is different than the first time location 312. Advantageously, thisallows for better coverage of noise sampling scans performed on thedisplay 102.

As next illustrated in block 512, and described with reference to FIGS.3A and 4 a second frequency from the plurality of frequencies with thelowest noise based on the second noise sampling scan 320 may bedetermined.

The second frequency may be the frequency of the plurality offrequencies with the lowest noise value. On the other hand, the noisevalues may be determined based on rolling averages of the noise levelsfor each of the plurality of frequencies in each noise sampling scan.

For example in the two sequence rotation example in FIG. 3A, the noisevalues determined in the second noise sampling scan 320 and the firstnoise sampling scan 304 may be averaged. The frequency of the pluralityof frequencies with the lowest average may be used as the secondfrequency.

As another example, in the four sequence rotation example in FIG. 4 ,the noise values determined in the fourth noise sampling scan 402, thesecond noise sampling scan 320, and the first noise sampling scan 304may be averaged. The frequency of the plurality of frequencies with thelowest average may be used as the second frequency.

As next illustrated in block 514, and described with reference to FIGS.3A and 4 , a second mutual sensing scan may be performed at the secondfrequency. In the second frame 316, because the second mutual sensingscan 308 occurs after the second noise sampling scan 320, the secondmutual sensing scan 308 may be performed at the second frequency.Advantageously, frequency hopping may be performed within a frame. Inother words, because the first mutual sensing scan 307 is performedbefore the second noise sampling scan 32 o, frequency hopping may beperformed within the second frame 316.

In various embodiments, the mutual sensing values determined in eachmutual sensing scan in each may be used to determine coordinates oftouch on the touchscreen in each corresponding frame. For example, inthe second frame 316 the first mutual sensing scan 307 and the secondmutual sensing scan 308 may be averaged to determine the touchcoordinates.

On the other hand a rolling average of mutual sensing scans may be usedto determine touch coordinates in each frame. For example in the twosequence rotation example in FIG. 3A, the touch coordinates in thesecond frame 316 may be determined based on the average between mutualsensing values determined in the first mutual sensing scan 307 in thefirst frame 302, the second mutual sensing scan 308 in the first frame302, the first mutual sensing scan 307 in the second frame 316, and thesecond mutual sensing scan 308 in the second frame 316. This may beapplied to each of the plurality of frames.

Also, in the four sequence rotation example in FIG. 4 , the touchcoordinates of the second frame 316 may be determined by the average ofthe mutual sensing values determined in the first mutual sensing scan307 in the fourth frame 410, the second mutual sensing scan 308 in thefourth frame 410, the first mutual sensing scan 307 in the first frame302, the second mutual sensing scan 308 in the first frame 302, thefirst mutual sensing scan 307 in the second frame 316, and the secondmutual sensing scan 308 in the second frame 316.

Example embodiments of the invention are summarized here. Otherembodiments can also be understood from the entirety of thespecification as well as the claims filed herein.

Example 1. A method for operating an electronic device, the methodincluding: displaying, on a display of the electronic device, an imageby sequentially displaying a plurality of frames of the image, theplurality of frames including a first frame and second frame;performing, on the display, a first noise sampling scan at a first timelocation within a first frame of the plurality of frames, the firstnoise sampling scan being performed at a plurality of frequencies;determining a first frequency from the plurality of frequencies with thelowest noise based on the first noise sampling scan; performing, on atouchscreen of the electronic device, a first mutual sensing scan at thefirst frequency; performing, on the display, a second noise samplingscan at a second time location within a second frame of the plurality offrames, the second noise sampling scan being performed at the pluralityof frequencies, the second time location being a different framelocation than the first time location; determining a second frequencyfrom the plurality of frequencies with the lowest noise based on thesecond noise sampling scan, the second frequency being different fromthe first frequency; and performing, on the touchscreen, a second mutualsensing scan at the second frequency.

Example 2. The method of example 1, further including: performing athird noise sampling scan at a third time location within a third frame,the third noise sampling scan being performed at the plurality offrequencies, the third time location being a different frame locationthan the first and the second time locations; performing a third mutualsensing scan at a third frequency of the plurality of frequencies basedon the third noise sampling scan; performing a fourth noise samplingscan at a fourth time location within a fourth frame, the fourth noisesampling scan being performed at the plurality of frequencies, thefourth time location being a different frame location than the first,the second, and the third time locations; and performing a fourth mutualsensing scan at a fourth frequency of the plurality of frequencies basedon the fourth noise sampling scan.

Example 3. The method of one of examples 1 or 2, further including:performing a third noise sampling scan at the first time location withina third frame; and performing a third mutual sensing scan at the firstfrequency based on the third noise sampling scan.

Example 4. The method of one of examples 1 to 3, where the first mutualsensing scan is performed within the first frame, and where the secondmutual sensing scan is performed within the second frame.

Example 5. The method of one of examples 1 to 4, where the values fromthe first mutual sensing scan and the second mutual sensing scan areincluded to obtain an average mutual sense value for the touchscreen atthe second frame, further including: detecting a touch of thetouchscreen during the second frame based on the average mutual sensevalue.

Example 6. The method of one of examples 1 to 5, where the first mutualsensing scan is performed within a first portion of the second frame andthe second mutual sensing scan are performed within a second portion ofthe second frame.

Example 7. The method of one of examples 1 to 6, where the values fromthe first mutual sensing scan and the second mutual sensing scan areincluded to obtain an average mutual sense value for the touchscreen atthe second frame, further including: detecting a touch of thetouchscreen during the second frame based on the average mutual sensevalue.

Example 8. The method of one of examples 1 to 7, further including:detecting a touch of the touchscreen during the second frame based on amutual sense value obtained from the second mutual sensing scan.

Example 9. The method of one of examples 1 to 8, performing the firstnoise sampling scan includes: sampling pixels of a portion of thedisplay at the plurality of frequencies to determine a noise level foreach sampling frequency.

Example 10. A device including: a display including a display layerincluding a plurality of pixels; a touchscreen including a touchscreencontroller; and a non-transitory memory storing instructions to beexecuted in the touchscreen controller to configure the touchscreencontroller to execute the example of claim 1.

Example 11. A method for operating an electronic device, the methodincluding: displaying, on a display layer of a touchscreen, an image bysequentially displaying a plurality of frames of the image; performing,by a touchscreen controller, a plurality of scans on the touchscreen ineach of the plurality of frames, each of the plurality of scansincluding a noise sampling scan performed on the display layer and amutual sensing scan performed on a touch sensing layer of thetouchscreen; determining, in each of the plurality of frames, a firstfrequency for a subsequent mutual-sensing scan from a plurality ofsampling frequencies based on noise levels determined during a previousnoise sampling scan; performing the subsequent mutual sensing scan atthe first frequency; and changing a sequence of each of the plurality ofscans after each of the plurality of frames.

Example 12. The method of example 11, where the noise sampling scan isperformed over a different portion of the display layer in consecutiveframes.

Example 13. The method of one of examples 11 or 12, where performing anoise sampling scan includes: sampling capacitances of pixels of aportion of the display layer, where sub-portions of the portion of thedisplay layer are each sampled at a different sampling frequency; anddetermining a noise level for each sampling frequency based on thecapacitances sampled in each corresponding sub-portion.

Example 14. The method of one of examples 11 to 13, where the pluralityof scans further includes a self-sensing scan and a further mutualsensing scan.

Example 15. The method of one of examples 11 to 14, where determiningthe first frequency includes: determining a noise level for each of theplurality of sampling frequencies used during the previous noisesampling scan; and determining a sampling frequency having the lowestnoise level to be the first frequency.

Example 16. The method of one of examples 11 to 15, where the pluralityof scans further includes a further mutual sensing scan, and wheremutual sensing touch values determined by the mutual sensing scan andthe further mutual sensing scan in each frame are averaged.

Example 17. The method of one of examples 11 to 16, where determiningthe first frequency includes: determining an average noise level foreach of the plurality of sampling frequencies in four preceding frames,the average noise levels being determined during noise sampling scansperformed in each of the four preceding frames; and determining asampling frequency having the lowest average noise level to be the firstfrequency.

Example 18. A device including: a display including a display layerincluding a plurality of pixels; a touchscreen including a touchscreencontroller; and a non-transitory memory storing instructions to beexecuted in the touchscreen controller to configure the touchscreencontroller to execute the method of example 11.

Example 19. A method for operating a touchscreen, the method including:displaying, on a display layer of a touchscreen, an image bysequentially displaying a plurality of frames of the image; performing,by a touchscreen controller, a plurality of scans on the touchscreen ineach of the plurality of frames, each of the plurality of scansincluding a noise sampling scan performed on the display layer and amutual sensing scan performed on a touch sensing layer of thetouchscreen, the noise sampling scan being performed at a plurality ofdifferent noise sampling frequencies, and a start time of the noisesampling scan in each of the plurality of frames being determined basedon a frame count of the frame being displayed within the plurality offrames; determining, based on the noise sampling scan for each frame, anoise sampling frequency from amongst the plurality of different noisesampling frequencies having a lowest noise level for that frame; andperforming, a mutual sensing scan that is performed subsequent to thenoise sampling scan at the noise sampling frequency having the lowestnoise level.

Example 20. The method of example 19, where the plurality of scansfurther includes a further mutual sensing scan, and where mutual sensingtouch values determined by the mutual sensing scan and the furthermutual sensing scan in each frame are averaged.

Example 21. The method of one of examples 19 or 20, where determiningthe noise sampling frequency includes: determining an average noiselevel for each of the plurality of different noise sampling frequenciesin four preceding frames, the average noise levels being determinedduring noise sampling scans performed in each of the four precedingframes; and determining a sampling frequency having the lowest averagenoise level to be the noise sampling frequency.

Example 22. The method of one of examples 19 to 21, where determiningthe noise sampling frequency includes: sampling capacitances of pixelsof a portion of the display layer of the touchscreen, where sub-portionsof the portion of the display layer are each sampled at a differentsampling frequency; determining a noise level for each samplingfrequency based on the capacitances sampled in each correspondingsub-portion; and determining the sampling frequency having the lowestnoise level.

Example 23. A device including: a display including a display layerincluding a plurality of pixels; a touchscreen including a touchscreencontroller; and a non-transitory memory storing instructions to beexecuted in the touchscreen controller to configure the touchscreencontroller to execute the method of example 19.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A method for operating an electronic device, themethod comprising: displaying, on a display of the electronic device, animage by sequentially displaying a plurality of frames of the image, theplurality of frames comprising a first frame and second frame;performing, on the display, a first noise sampling scan at a first timelocation within a first frame of the plurality of frames, the firstnoise sampling scan being performed at a plurality of frequencies,wherein performing the first noise sampling scan comprises samplingcapacitances of pixels of a portion of the display, wherein sub-portionsof the portion of the display are each sampled at a different samplingfrequency, and determining a noise level for each sampling frequencybased on the capacitances sampled in each corresponding sub-portion;determining a first frequency from the plurality of frequencies with thelowest noise based on the first noise sampling scan; performing, on atouchscreen of the electronic device, a first mutual sensing scan at thefirst frequency; performing, on the display, a second noise samplingscan at a second time location within a second frame of the plurality offrames, the second noise sampling scan being performed at the pluralityof frequencies, the second time location being a different framelocation than the first time location; determining a second frequencyfrom the plurality of frequencies with the lowest noise based on thesecond noise sampling scan, the second frequency being different fromthe first frequency; and performing, on the touchscreen, a second mutualsensing scan at the second frequency.
 2. The method of claim 1, furthercomprising: performing a third noise sampling scan at a third timelocation within a third frame, the third noise sampling scan beingperformed at the plurality of frequencies, the third time location beinga different frame location than the first and the second time locations;performing a third mutual sensing scan at a third frequency of theplurality of frequencies based on the third noise sampling scan;performing a fourth noise sampling scan at a fourth time location withina fourth frame, the fourth noise sampling scan being performed at theplurality of frequencies, the fourth time location being a differentframe location than the first, the second, and the third time locations;and performing a fourth mutual sensing scan at a fourth frequency of theplurality of frequencies based on the fourth noise sampling scan.
 3. Themethod of claim 1, further comprising: performing a third noise samplingscan at the first time location within a third frame; and performing athird mutual sensing scan at the first frequency based on the thirdnoise sampling scan.
 4. The method of claim 1, wherein the first mutualsensing scan is performed within the first frame, and wherein the secondmutual sensing scan is performed within the second frame.
 5. The methodof claim 4, wherein the values from the first mutual sensing scan andthe second mutual sensing scan are included to obtain an average mutualsense value for the touchscreen at the second frame, further comprising:detecting a touch of the touchscreen during the second frame based onthe average mutual sense value.
 6. The method of claim 1, wherein thefirst mutual sensing scan is performed within a first portion of thesecond frame and the second mutual sensing scan are performed within asecond portion of the second frame.
 7. The method of claim 6, whereinthe values from the first mutual sensing scan and the second mutualsensing scan are included to obtain an average mutual sense value forthe touchscreen at the second frame, further comprising: detecting atouch of the touchscreen during the second frame based on the averagemutual sense value.
 8. The method of claim 1, further comprising:detecting a touch of the touchscreen during the second frame based on amutual sense value obtained from the second mutual sensing scan.
 9. Adevice comprising: a display comprising a display layer comprising aplurality of pixels; a touchscreen comprising a touchscreen controller;and a non-transitory memory storing instructions to be executed in thetouchscreen controller to configure the touchscreen controller toexecute the method of claim
 1. 10. The method of claim 1, wherein thefirst time location has a start time for the first noise sampling scanin the first frame, and the second time location has a start time forthe second noise sampling scan in the second frame, and wherein thestart time for the second noise sampling scan is different from thestart time for the first noise sampling scan.
 11. A method for operatingan electronic device, the method comprising: displaying, on a displaylayer of a touchscreen, an image by sequentially displaying a pluralityof frames of the image; performing, by a touchscreen controller, aplurality of scans on the touchscreen in each of the plurality offrames, each of the plurality of scans including a noise sampling scanperformed on the display layer and a mutual sensing scan performed on atouch sensing layer of the touchscreen, the noise sample scan and themutual sensing scan being performed in a sequence, wherein performing anoise sampling scan comprises sampling capacitances of pixels of aportion of the display layer, wherein sub-portions of the portion of thedisplay layer are each sampled at a different sampling frequency, anddetermining a noise level for each sampling frequency based on thecapacitances sampled in each corresponding sub-portion; determining, ineach of the plurality of frames, a first frequency for a subsequentmutual-sensing scan from a plurality of sampling frequencies based onnoise levels determined during a previous noise sampling scan;performing the subsequent mutual sensing scan at the first frequency;and changing the sequence of each of the plurality of scans after eachof the plurality of frames.
 12. The method of claim 11, wherein thenoise sampling scan is performed over a different portion of the displaylayer in consecutive frames.
 13. The method of claim 11, wherein theplurality of scans further includes a self-sensing scan and a furthermutual sensing scan.
 14. The method of claim 11, wherein determining thefirst frequency comprises: determining a noise level for each of theplurality of sampling frequencies used during the previous noisesampling scan; and determining a sampling frequency having the lowestnoise level to be the first frequency.
 15. The method of claim 11,wherein the plurality of scans further includes a further mutual sensingscan, and wherein mutual sensing touch values determined by the mutualsensing scan and the further mutual sensing scan in each frame areaveraged.
 16. The method of claim 11, wherein determining the firstfrequency comprises: determining an average noise level for each of theplurality of sampling frequencies in four preceding frames, the averagenoise levels being determined during noise sampling scans performed ineach of the four preceding frames; and determining a sampling frequencyhaving the lowest average noise level to be the first frequency.
 17. Adevice comprising: a display comprising a display layer comprising aplurality of pixels; a touchscreen comprising a touchscreen controller;and a non-transitory memory storing instructions to be executed in thetouchscreen controller to configure the touchscreen controller toexecute the method of claim
 11. 18. The method of claim 11, wherein thechanging of the sequence changes a start time of the noise sampling scanin each frame relative to a start time of a previous noise sampling scanin a previous frame.
 19. A method for operating a touchscreen, themethod comprising: displaying, on a display layer of a touchscreen, animage by sequentially displaying a plurality of frames of the image;performing, by a touchscreen controller, a plurality of scans on thetouchscreen in each of the plurality of frames, each of the plurality ofscans including a noise sampling scan performed on the display layer anda mutual sensing scan performed on a touch sensing layer of thetouchscreen, the noise sampling scan being performed at a plurality ofdifferent noise sampling frequencies, and a start time of the noisesampling scan in each of the plurality of frames being determined basedon a frame count of the frame being displayed within the plurality offrames; determining, based on the noise sampling scan for each frame, anoise sampling frequency from amongst the plurality of different noisesampling frequencies having a lowest noise level for that frame; andperforming, a mutual sensing scan that is performed subsequent to thenoise sampling scan at the noise sampling frequency having the lowestnoise level.
 20. The method of claim 19, wherein the plurality of scansfurther includes a further mutual sensing scan, and wherein mutualsensing touch values determined by the mutual sensing scan and thefurther mutual sensing scan in each frame are averaged.
 21. The methodof claim 19, wherein determining the noise sampling frequency comprises:determining an average noise level for each of the plurality ofdifferent noise sampling frequencies in four preceding frames, theaverage noise levels being determined during noise sampling scansperformed in each of the four preceding frames; and determining asampling frequency having the lowest average noise level to be the noisesampling frequency.
 22. The method of claim 19, wherein determining thenoise sampling frequency comprises: sampling capacitances of pixels of aportion of the display layer of the touchscreen, wherein sub-portions ofthe portion of the display layer are each sampled at a differentsampling frequency; determining a noise level for each samplingfrequency based on the capacitances sampled in each correspondingsub-portion; and determining the sampling frequency having the lowestnoise level.
 23. A device comprising: a display comprising a displaylayer comprising a plurality of pixels; a touchscreen comprising atouchscreen controller; and a non-transitory memory storing instructionsto be executed in the touchscreen controller to configure thetouchscreen controller to execute the method of claim
 19. 24. A methodfor operating an electronic device, the method comprising: displaying,on a display layer of a touchscreen, an image by sequentially displayinga plurality of frames of the image; performing, by a touchscreencontroller, a plurality of scans on the touchscreen in each of theplurality of frames, each of the plurality of scans including a noisesampling scan performed on the display layer and a mutual sensing scanperformed on a touch sensing layer of the touchscreen, the noise samplescan and the mutual sensing scan being performed in a sequence;determining, in each of the plurality of frames, a first frequency for asubsequent mutual-sensing scan from a plurality of sampling frequenciesbased on noise levels determined during a previous noise sampling scan,wherein determining the first frequency comprises: determining anaverage noise level for each of the plurality of sampling frequencies infour preceding frames, the average noise levels being determined duringnoise sampling scans performed in each of the four preceding frames, anddetermining a sampling frequency having the lowest average noise levelto be the first frequency; performing the subsequent mutual sensing scanat the first frequency; and changing the sequence of each of theplurality of scans after each of the plurality of frames.